Evaporating coil structure for refrigerating systems



N. H. GAY

Sept. 12, 1933.

EVAPORATING COIL STRUCTURE FOR REFRIGERATING SYSTEMS Filed Dec. 28, 1931 (Ittorneg '8 Patented Sept. 12, 1933 Y UNIT -D(STATE EVAPORATING COIL STRUCTURE FOR BEFRIGERATING SYSTEMS Norman H. Gay, Los Angeles, Calif.

Application December 28, 1931 Serial No. 583,518

9 Claims. (01. 62126) This invention concerns a construction of evaporating coils for refrigerating systems in which a free'flow of refrigerant is provided between inlet and outlet headers'and back again,

and concerns certain modifications of the structures shown in my Patents Nos. 1,715,828 of June 4, 1929 and 1,794,110 of February 24, 1931.

In these prior patents I have disclosed a refrigerating "or evaporating coil for refrigerator systems in which an inlet and an outlet header.

are provided with U-shaped coils connecting the 110, the accumulator is illustrated as a'connection between the inlet and outlet headers and has an upper member on the outlet header for the purpose of separating the'refrigerant gas.

,According to the present invention, the upper oroutlet header. is made of larger diameterthan the inlet header, andthis in itself provides a space 'same'may remain substantially quiescent for. a period, during which'the' gaseous refrigerant is separated therefrom and passes to the upper space .3 of thisoutlet header, from vvhich'it maybe drawn foifin the usual way.

Another feature of the present invention is the provision of evaporation coils connecting the headers which are of greater section at the connection tothe outlet header thanat the connec- 7 tion to'the inlet new These and other featuresof thefinvention will appear in the course ofthe followingspecification 740 and claims in; connection with the drawing which illustrates one formof construction of an evaporator according-to the present invention.

Inthe drawingz. Figure lis an end elevation'of an evaporator,

. in cycle with the compressor, condenser and receiver. g Figure 2 isa sectional view substantially on line 2-'- 2 of Figure 1. Q in my prior patents, the compressor 10 is connectedby 'a pipe line 11 with a condenser 12 V which delivers condensed liquid refrigerant by a pipe 13 into acombined receiver and oil trap 14 "from which the liquid refrigerant flows through .a pipe 15 past an expansion valve 16. 'Trapped'oilmay flow off through 'a pipe 17 controlledby'a"valvel8.

- The evaporatingcoil according to the present invention is' illustrated as enclosed within the Walls 20 and floor 21 of the brine tank.

with a diagrammatic showing of its connection The pipe 15 leads into a lower or inlet header 25 from which, in the illustrated form, are branched the pluralities of evaporating coils 26, which are shown in Figure 1 as each being located substantially in a vertical plane extend- 6 ing at right angles to the axis of the inlet header 25; the area of cross section at the connection to the inlet header being less than the cross section atthe connection to the outlet header; In Figure 2, each of the coil sets 26 is illustrated as comprising two pipes 2'7, 28 which communicate with the inlet header 25, and which are connected to the upper or outlet header 29. The pipes 2'7 are branched intermediate their length to form the branch pipes 27a, 27b and 28a, 28b. In the form of construction shown, this is accomplished by having ,the pipes 27, 27a, 27b and 28, 28a, 28b of the same diameter throughout.

The pipes 27, 28 are substantially horizontal, with a slight upward inclination in their runs 1. away from the inlet header 25, and may be formed integral with the pipes 27a, 28a by bendinglthe upper runs of pipes 27a and28a likewise having 'a slight upward inclination to the Sr connection with the outlet heade" 29, t f '1- within which the liquid refrigerant entering t e 1 o lam 1 tate the'free movement of the refrigerant from the inlet to the outlet header 29. The pipes 27b, 28b are branched from pipes 2'7, 28 at the awe-r1 substantially horizontal portion of these 'pipes r The two headers are connected likewise by large interconnections 30,- 31 so that liquid refrigerant passing into the upper header may flow directly back into the lower header, by

. gravity.

In operation, as the liquid refrigerant from the receiver 14 .passes by pipe 15 and valve 16 into the lower header, it establishes a liquid level to substantially half the height of the upper or outlet header 29. Due to the large area of exposure of-the coils 26 to the brine in the brine tank, these coils 26 absorb heat from the brine, and transfer it to the liquid refrigerant existing in the coils, thus evaporating a portion 5 of the-liquid refrigerant. The mixed gaseous and liquid refrigerant then moves upward in the coils, and establishes a rapid circulation from the inlet header through the pipes of the respective coils to the outlet header, and the'liquid refrigerant thencegoes back by interconnections 30, 31 to the inlet header for return in cycle. Owing to the large diameter of the outlet header, the liquid remains in substantial quiescence in the upper header for a time sufficient to per- .mit the separation and escape of gaseous refrigerant therefrom, before the liquid refrigerant has passed into the inlet header and then to the coils again, and preferably before the liquid refrigerant passes downward in the interconnections 30, 31.

It has been found by experience that the heat transfer in refrigerating coils increases as the speed of the liquid refrigerant passing through the coils increases. By providing a greater cross section, for example, by the pipes 27a, 27b, and 28a and 28b, at the connection to the outlet header 29 than is the cross section of pipes 2'7 and 28 at the connection to the inlet header 25, the increase in volume caused by the evaporation of liquid refrigerant occurring in the coils themselves, whereby the volume of combined gaseous and liquid refrigerant is greater than the volume of liquid refrigerant entering the pipes 27 and 28 from the inlet header 25, there is a compensation by the increasedcross sectional area of pipes 27a, 27b, and 28a, 28b, and hence a more rapid flow of refrigerant occurs in the lower runs, i. e. in pipes 27 and 28 to the branches. Therefore, on the one hand the flow through the lower runs is not retarded by the back pressure of the increasing volume of refrigerant due to evaporation, and on the other hand the ample cross section afforded this increased volume permits it to flow at a greater rate.

In particular, it will be noted that in the illustrated form no attempt need be made to separate gaseous and liquid refrigerant in the evaporating coils themselves; and hence full advantage can be taken of the lesser density of the 'mixed gaseous and liquid refrigerant for causing a rapid circulation through the coils, headers and return connection, and this rapid circulation in itself serves to restrict any separation from occurring in the coils themselves.

The inlet header 25 may be provided with a baffle .40 if desired, so that a substantially quiescence beneath the same may exist, and an oil withdrawal pipe 41 may be provided to remove trapped oil from the inlet header.

It is obvious that the invention is not limited solely to the form of execution shown but that it may be modified and employed in many ways within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Pat ent, is:

1. An evaporator structure for. refrigerating systems comprising a lower inlet header, an upper outlet header of larger cross section than said inlet header, evaporating coils connecting the said headers toprovide a flow of refrigerant between said inlet header and saidoutlet header, each said coil comprising a branched conduit having a single connection to said inlet header and a plurality of connections to the outlet header, and a liquid refrigerant return connection from said outlet to said inlet header, said outlet header being of large cross section with respect to said coils whereby to assure a period of substantial quiescence in the circulation of the liquid refrigerant so that gaseousrefrigerant may separate therefrom in said outlet header.

2. An evaporator structure for a refrigerating system comprising inlet and outlet headers, evaporating coils for establishing communication between said headers, at least one of said coils comprising a branched conduit having a single connection to said inlet header and a plurality of connections to the outlet header, and a liquid refrigerant return connection between said headers.

3. An evaporator structure for a refrigerating system comprising inlet and outlet headers, and an evaporator coil for establishing communication between the headers, said coil comprising a pipe communicating with said inlet header and branching along its length into a plurality of pipes which communicate with said outlet header.

4; An evaporator structure as in claim 3, in which said coil has a substantially horizontal runway from the inlet header and at least one branch occurs along such run.

5. An evaporator structure for a refrigerating system comprising inlet and outlet headers, an evaporator coil for establishing communication between the headers, said coil comprising a pipe communicating with said inlet header and branching along its length into a plurality of pipes which communicate with said outlet header, and a liquid refrigerant return connection be-- tween said outlet and inlet headers.

6. An evaporator structure for a refrigerating system including a lower inlet headen'an upper outlet header of larger cross section, and a plurality of evaporating coils for establishing communication between said headers, at least one of said coils being branched between the inlet header and the outlet header and having a greater section at its connections to the outlet header than at its connection to the inlet header, and a liquid refrigerant gravity return connection from said outlet to said inlet header, said outlet header having a large cross section with respect to said coils whereby to permit a substantial quiescence of the refrigerant in said outlet header so that gaseous refrigerant may become separated from liquid refrigerant" therein.

7. An evaporator structure for a refrigerating system comprising inlet and outlet headers, said outlet header beinglocated' at a higher level thansaid inlet header andparallel thereto,a plurality of evaporating coil systems located inplanes at right angles to the axes of said inlet and outlet headers, each said system including at least one evaporating coil including a branched conduit having a'greater number of connections to the outlet header than to the'inlet header, and a liquid refrigerant return connection between said headers.

8. An evaporator structure for arefri'gerating system comprising a low inlet header, an upper outlet header, a plurality of evaporating coils for establishing communication between said headers, each of said coils including asubstantially U-shaped portion with upper and lower legs which are substantially horizontal and a furtherand branched portion extending from the lower leg to the outlet header, and a liquid refrigerant gravity return connection from said outlet to said inlet header. 7

9. An evaporator structure for a refrigerating system comprising inlet and outlet headers, said outlet header being located at a higher levelthan said inlet header and parallel thereto, a plurality of evaporating coil systems each located in a plane at right angles to the axis of said inlet and outlet headers, each said system including a plurality of branched conduits each having a U- shaped portion with the legs horizontal and a branched-connection from the lower horizontal return connection between said'headers.

NORMAN H. GAY. 

